Petals Documentation > Petals ESB > Petals Components > Components User Guide > Petals-SE-Talend

Petals-SE-Talend

( this is a first draft )

Features

This Service-Engine (SE) allows to expose Talend jobs as services into Petals and to execute them inside the bus.
This component supports jobs created with both Talend Open Studio and Talend Integration Suite. It also provides several mechanisms to pass information and data to a job.

Before going further, it must be clear that no configuration for this component is intended to be created by hand.
And neither by the Petals Studio. In fact, only Talend Open Studio and Talend Integration Suite have the ability to generate a correct configuration for this component.
However, which one of these tool created the configuration is not important for this service-engine.

Two catagories of Talend jobs can be distinguished in the scope of Petals:

  • Simple jobs, or classic jobs, are Talend jobs that do not need any specific interaction with Petals. Everything they need is in the job context and content.
  • Petals jobs, are Talend jobs that may interact with the Petals-SE-Talend component.

Classic Talend jobs

Talend jobs for Petals

Those created with Talend Open Studio

Those created with Talend Integration Suite

In this former category, the permitted interactions depend on the job's content.
Basically, there are five kinds of interactions:

  • Input parameters
    • Context overriding: the service defines the contexts that can be overriden. You can use this mechanism to pass information or data to the job.
    • File attachments: the service may expect attachments in input.
    • Raw data: the service may also expect a flow of data rows to process inside the job. This mechanism relies on a Talend component called tPetalsInput.
  • Output parameters
    • The execution result: any executed job returns

For more information, please refer to the use cases.

Component Configuration

Before installing the bc-ejb component, you must check in your ${PETALS_HOME}/conf/server.properties configuration file if the property "petals.classloaders.isolated=true" is set and uncommented. The BC-EJB component need the isolated classloaders to work correctly.

The component can be configured through its JBI descriptor file like this :

<?xml version="1.0" encoding="UTF-8"?>
<jbi:jbi xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:petalsCDK="http://petals.ow2.org/components/extensions/version-4.0"
    xmlns:jbi="http://java.sun.com/xml/ns/jbi" version="1.0">

  <jbi:component type="binding-component" component-class-loader-delegation="parent-first">

    <jbi:identification>
      <jbi:name>petals-bc-ejb</jbi:name>
      <jbi:description>an EJB Binding Component sending messages to local or distant EJB instances</jbi:description>
    </jbi:identification>

    <jbi:component-class-name>org.ow2.petals.bc.ejb.EjbBC</jbi:component-class-name>
    <jbi:component-class-path>
      <jbi:path-element/>
    </jbi:component-class-path>
    <jbi:bootstrap-class-name>org.ow2.petals.component.framework.DefaultBootstrap</jbi:bootstrap-classname>
    <jbi:bootstrap-class-path>
      <jbi:path-element/>
    </jbi:bootstrap-class-path>

    <petalsCDK:acceptor-pool-size>5</petalsCDK:acceptor-pool-size>
    <petalsCDK:processor-pool-size>10</petalsCDK:processor-pool-size>
    <petalsCDK:ignored-status>NOTHING_IGNORED</petalsCDK:ignored-status>
    <shared-library>petals-sl-ejb</shared-library>
    <petalsCDK:jbi-listener-class-name>org.ow2.petals.bc.ejb.listener.JBIListener</petalsCDK:jbi-listener-class-name>
  </jbi:component>
</jbi:jbi>

This component doesn't have any specific configuration parameters. 

You can customize the component configuration by changing the following common parameters.

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EJB binding component can only handle outgoing message (JBI -> EJB), so you can't specify an external-listenerclass-name.

Service Configuration

Send a JBI message to an external EJB

When a JBI message is received on an endpoint linked to an EJB, the message is transformed into a RMI message, then sent to the linked EJB.

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The RMI message is created following these steps :

  1. The JBI message payload is mapped to Java objects. These objects (and their types) are used as operation parameters for the RMI call. The mapping is done thanks to the PEtALS-JAXB-Databinding library. For more information about XML databinding feel free to read the chapter entitled XML to Java binding.
  2. The JBI message exchange operation local part is used as the EJB method to invoke.
  3. If a security subject is provided by the JBI message it is used as authentication information during the RMI invokation.
For more information about JAAS read the chapter : JAAS authentication for EJB calls

In order to reach the remote EJB, the component need to get an RMI stub of the EJB from a JNDI server. The JNDI name of the target EJB is defined in the parameter ejb.jndi.name.

The external EJB is called and the response is processed by the PEtALS-JAXB-Databinding library and then returned to the JBI environment.

Service Unit descriptor

The Service Unit descriptor file ( jbi.xml ) looks like this :

<?xml version="1.0" encoding="UTF-8"?>

<!--
  JBI descriptor for the PEtALS' "petals-bc-ejb" component (EJB).
  Originally created for the version 1.1 of the component.
-->

<jbi:jbi version="1.0"
    xmlns:ejb="http://petals.ow2.org/components/ejb/version-1.1"
    xmlns:generatedNs="http://application.localisation.watersupply.petals.ow2.org/"
    xmlns:jbi="http://java.sun.com/xml/ns/jbi"
    xmlns:petalsCDK="http://petals.ow2.org/components/extensions/version-4.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

  <!-- Import a Service into PEtALS or Expose a PEtALS Service => use a BC. -->
  <jbi:services binding-component="true">

    <!-- Import a Service into PEtALS => provides a Service. -->
    <jbi:provides
        interface-name="generatedNs:LocalisationFinderBusinessServicePortType"
        service-name="generatedNs:LocalisationFinderBusinessService"
        endpoint-name="LocalisationFinderBusinessServiceEndpoint">

      <!-- CDK specific elements -->
      <petalsCDK:wsdl>Localisation.wsdl</petalsCDK:wsdl>

      <!-- Component specific elements -->
      <ejb:ejb.jndi.name>LocalisationFinderBusinessService</ejb:ejb.jndi.name>
      <ejb:java.naming.factory.initial>org.jnp.interfaces.NamingContextFactory</ejb:java.naming.factory.initial>
      <ejb:java.naming.provider.url>jnp://localhost:1099/</ejb:java.naming.provider.url>
      <ejb:ejb.version>2.1</ejb:ejb.version>
      <ejb:ejb.home.interface>org.ow2.petals.watersupply.localisation.application.LocalisationFinderBusinessServiceRemoteHome</ejb:ejb.home.interface>
      <ejb:marshalling.engine>jaxb</ejb:marshalling.engine>
      <ejb:security.name />
      <ejb:security.principal />
      <ejb:security.credencials />

    </jbi:provides>
  </jbi:services>
</jbi:jbi>

Configuration of a Service Unit to expose an EJB onto Petals ESB :

Parameter Description Default Required
ejb.jndi.name The JNDI name of the targeted EJB - Yes
java.naming.factory.initial The name of the targeted JNDI Initial Context Factory - Yes
java.naming.provider.url The URL of the targeted JNDI service - Yes
ejb.version Implemention version of the targeted EJB.
Supported versions are 2.0, 2.1, 3.0 and 3.1 		- Yes
ejb.home.interface Fully qualified name of the targeted EJB Home Interface. Used only
with ejb 2.0 and 2.1.
Fully qualified name of the targeted EJB Home Interface. Used only with ejb 2.0 and 2.1. 		- No
security.name Fully qualified name of the security module used. - No
security.principal Username - No
security.credencials Password - No
marshalling.engine The marshalling engine to use jaxb Yes

Configuration of a Service Unit to provide a service (JBI)

Parameter Description
Default
Required
provides Describe the JBI service that will be exposed into the JBI bus. Interface (QName), Service (QName) and Endpoint (String) attributes are required. - Yes

Configuration of a Service Unit to provide a service (CDK)

Parameter Description
 Default
 Required
timeout Timeout in milliseconds of a synchronous send. This parameter is used by the method sendSync (Exchange exchange) proposes by the CDK Listeners classes.
Set it to 0 for an infinite timeout. 		30000 No
exchange-properties This sections defines the list of properties to set to the JBI exchange when processing a service. - No
message-properties This sections defines the list of properties to set to the JBI message when processing a service. - No
validate-wsdl Activate the validation of the WSDL when deploying a service unit. true No
wsdl
Path to the WSDL document describing services and operations exposed by the provided JBI endpoints defined in the SU.
The value of this parameter is :
  • an URL
  • a file relative to the root of the SU package
    If not specified, a basic WSDL description is automaticaly provided by the CDK.
- No
forward-attachments
Defines if attachment will be forwarded from IN message to OUT message.
false No
forward-message-properties
Defines if the message properties will be forwarded from IN message to OUT message. false No
forward-security-subject
Defines if the security subject will be forwarded from IN message to OUT message. false No

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Service Unit content 

The service unit must contain a JAR archive including the EJB Interface (and EJB Home Interface for a 2.x EJB) and all specific Java classes used by this interface.

It is also highly recommended to provide a WSDL description of your EJB interface. This WSDL description will be used as Service Description for the JBI Endpoint linked to your EJB.

The directory structure of a SU for the BC-EJB must look like this :

my-su-ejb.zip
   + META-INF
     - jbi.xml
   - my-ejb-wsdl-description.wsdl
   - my-ejb.jar
   - my-ejb-dependency1.jar
   - my-ejb-dependency2.jar


h2. Provider restrictions


h2. Provider usage

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